1. Field of the Invention
The present invention relates to bases and contour measuring systems using the same, and particularly to, a base and a contour measuring system using the same with a high measuring precision.
2. Discussion of the Related Art
A contour measuring probe is used for measuring a figure of a precision element, such as an optical element. However, when measuring, the contour measuring probe must be kept in touch with the precision element when the contour measuring probe moves relative to a moving precision element. Generally, the contour measuring probe is fixed to a base, and follows a movement of the base.
Referring to FIG. 7, a base 10 includes a non-slidable platform 11, a saddle member 12, and a slidable platform 13. A pair of first guide rails 111 are fixed on the non-slidable platform 11 extending in a direction parallel to a Y-axis. The saddle member 12 is disposed on the first guide rails 111 and moves along the first guide rails 111. A pair of second guide rails 121 are fixed on the saddle member 12 extending in a direction parallel to an X-axis. The slidable platform 13 is disposed on the second guide rails 121 and moves along the second guide rails 121. A contour measuring probe 20 is fixed on the slidable platform 13. A tip extension 201 of the contour measuring probe 20 moves in a direction parallel to a Z-axis. The contour measuring probe 20 can move along the X-axis via a movement of the slidable platform 13, and can move along the Y-axis via a movement of the saddle member 12. In a measuring process, the contour measuring probe 20 moves along the X-axis or the Y-axis while the tip extension 201 of the contour measuring probe 20 moves along the Z-axis driven by a small measuring force to remain in touch with an optical element 30.
However, the tip extension 201 of the contour measuring probe 20 cannot extend along the Z-axis after fixed on the slidable platform 13, because a surface of the slidable platform 13 is generally not smooth and a limitation of a machining precise of the guide rails 111, 121. Since the tip extension 201 of the contour measuring probe 20 is slanted relative to the Z-axis, the displacement information of the tip extension 201 cannot reflect a change of a height along the Z-axis of the optical element 30, thereby a measuring precision of the contour measuring probe 20 decreases.
Therefore, a new base and a contour measuring system using the same which can overcome the above-described problem are desired.